Hematopoietic stem cells (HSCs) are rare stem cells that have the ability to differentiate into specialized blood cells, including lymphocytes, red blod cells, and platelets. HSCs are used in clinical transplantation protocols to treat a variety of diseases, including leukemia, inborn anomalies of the blood and immune system, aplastic anemia, and hemoglobinopathies. However, finding a matching donor is difficult, time consuming, and especially problematic for African Americans, Hispanics, Native Americans, and people of mixed ethnicity. Currently, only 1 in 3 patients will find a suitable donor; thus, many patients die before finding an appropriate match. While studies to successfully expand these cells have spanned over the last three decades, a routine method for ex vivo expansion of human HSCs is still not available and has been met with limited success for clinical applications. We hypothesize that both intrinsic and extrinsic factors play key roles in obtaining a suitable population of HSCs/HPCs (hematopoietic progenitor cells) for successful bone marrow transplantation. If successful, the proposed innovative approach has the potential to transform the field of bone marrow transplantation, and offers a curative option for patients with a wide spectrum of diseases including hematologic cancers, immune deficiency disorders, and aplastic anemia. The Specific Aims of our proposal are focused on achieving this objective. Aim 1. To determine if there is a synergistic effect between ICD-NOTCH and a hydrogel extracellular matrix in promoting definitive HSC/HPC expansion of human umbilical cord blood (hUCB). Aim 2. To compare if expansion approaches of hUCB that utilize ICD-NOTCH, SALL4, and a hydrogel extracellular matrix in combination will promote higher efficiency of short- term and long-term repopulation to marrow recovery.